1. Field of the Invention
This invention pertains to the field of backpacks of the type that can be worn on a person's back or over a person's shoulder. More particularly, this invention pertains to a wheeled-backpack having a unique, non-rigid or flexible connection between a rigid wheeled base of the backpack and a supporting backing sheet of the backpack that rests against a person's back when worn. The flexible connection allows the base and backing sheet to move relative to each other as the backpack wearer's upper body moves, enabling the backpack to be more comfortably worn. Additionally, a unique curved extendable towing member is utilized that follows the curvature of the backpack wearer's back to further enhance the comfort of wearing the backpack.
2. Background of the Invention
It is common for many varieties of baggage to be equipped with wheels that enable the baggage to be towed by persons when traveling. A typical towable piece of baggage generally includes a pair of wheels and an extendable towing member connected to the piece of baggage.
A typical wheeled-suitcase, for example, has wheels that are only a few inches in diameter. The wheels are usually mounted spaced apart on an edge of the suitcase where they can support the suitcase above the ground when the suitcase is tilted and towed. Although some suitcase have retractable wheels and some have casters, most suitcases have wheels that are fixed in a single orientation relative to an edge of the suitcase.
It is also common for the wheels of such towable baggage to be mounted to a rigid base of the piece of baggage. The rigid base has sufficient stiffness to support the wheels in their fixed orientation and to support the weight of the piece of baggage and its contents when being towed. In the case of a rigid wheeled-suitcase having a shell made of plastic, aluminum, or other generally stiff material, the rigid base is often merely a portion of the suitcase exterior. Conversely, baggage made mostly of canvas, nylon, leather, or other flexible materials generally utilize some form of stiffening frame or rigid base adjacent the exterior of the baggage for supporting the weight and holding the wheels in their fixed orientation.
As mentioned above, a wheeled pieced of baggage also commonly includes some form of towing member with a towing handle that is extendable from the piece of baggage. Extension of the towing member allows the piece of baggage to be pulled behind a person without coming into contact with the person's legs and feet as the piece of baggage is being towed.
In many cases, a wheeled piece of baggage has an extendable towing member comprised of a pair of parallel telescoping poles bridged by the towing handle. The poles slide into separate vertically oriented tubular receptacles rigidly attached to an interior compartment of the piece of the baggage. In such a configuration, the towing member least interferes with the internal compartment of the piece of baggage and is generally not visible from the exterior of the piece of baggage when stowed or retracted. Other types of baggage utilize single-pole telescoping tow members that extend and retract from a single tubular receptacle that is centrally positioned between the wheels of the piece of baggage.
Yet other types of baggage utilize non-telescoping extendable towing members such as bars or poles that are hinged to the piece of baggage. Typically, such pieces of baggage have some form of clasp that holds the towing member against a side of the piece of baggage when the baggage is not being towed and that releases the towing member when desired to allow the towing member to pivot upwardly into an extended position. Such towing members can also usually be locked into a particular extended position.
Providing baggage such as overnight luggage or suitcases with wheels has increased in popularity and their convenience has been appreciated to the extent that recently, wheels have begun being provided on other types of baggage such as backpacks. However, most backpacks have merely been provided with the same type of wheeled towing systems commonly utilized with conventional baggage as described above. Prior art wheeled-backpacks provided with conventional towing systems suffer from disadvantages due to their different design and construction from that of other types of baggage such as suitcases, and due to their commonly being worn on the back of the user unlike other types of baggage.
One such disadvantage is that, unlike suitcases, it is desirable that a backpack be able to flex, especially on the portion of the backpack that rests against a person's back when being worn. This is because, as a person walks, the person's shoulders rotate relative to his or her hips, thereby causing his or her back to twist. Like wheeled-suitcases, conventional wheeled-backpacks typically have an extendable towing member rigidly attached to the base of the backpack. This is because it was generally thought in the art that the towing member must be rigidly attached to the base of the piece of baggage to effectively be used to tilt and tow the piece of baggage along the ground. However, the rigid construction of prior art wheeled-backpacks is disadvantaged in that, as a person walks while wearing such a backpack, portions of the backpack are unable to maintain contact against the person's back and thereby cause discomfort as they intermittently contact the person's back. Additionally, as a wearer climbs stairs or leans to one side such as when reaching down to pick up another item, one of the wearer's shoulders is momentarily closer to the wearer's hips than the other. In this situation, depending upon the particular configuration of the backpack, either the bottom or the top of the backpack will slide from side to side causing additional discomfort. These aspects of prior art wheeled-backpacks cause such backpacks to feel more like strapped on suitcases rather than conventional non-wheeled-backpacks which are soft sided and much more comfortable.
In addition to the disadvantages in comfort, the rigid construction of prior art wheeled-backpacks also suffers from structural disadvantages. Unlike suitcases that typically have a rigid rectangular frame or shell for maintaining the shape of the suitcase which also is used to adequately support the towing member, prior art wheeled-backpacks generally lack such a support. Thus, the towing member of a prior art wheeled-backpack is typically supported by the rigid base of the backpack on which the wheels are mounted. In this configuration, the towing member acts as a leverage arm creating large stresses at the union between the towing member and the base even during normal towing. Additional stresses are generated when the wheels of such a backpack attempt to move independently of the towing member, such as when one wheel encounters an obstruction when the backpack is being towed. In such a situation, one of the wheels typically rides over the obstruction while lifting the other wheel above the ground, thereby causing torsional loading of the towing member. To withstand these loads, the base of the towing member of a typical prior art backpack is made substantially strong and durable, which limits the materials that may used to construct the backpack and which influences the weight of the backpack.
Yet another disadvantage associated with any type of wheeled baggage having a rigid construction is that they are prone to tipping over when being towed around corners. This tendency to tip is due to the towing member functioning as a lever arm which causes a large torque to act upon the baggage when even small forces are applied to the towing handle.